5 Health Conditions That Can Cause Heartburn

What's causing your heartburn?

When the valve that separates the stomach from the esophagusthe lower esophageal sphincter, or LESisn’t closed tightly, it can lead to heartburn.

"The LES has to relax to allow the meal to go down," says Kenneth R. DeVault, MD, professor of gastroenterology and chair of the department of medicine at the Mayo Clinic, in Jacksonville, Fla. "But when those relaxations become too many or occur at the wrong time, that allows acid to reflux."